Studies of stoichiometry, energetics and kinetics of electron transfer reactions are being conducted for the purpose of understanding the mechanism of biological electron transfer components. Efforts are presently concentrated on the components such as the heme proteins (cytochrome c and cytochrome c oxidase) in the mammalian respiratory system. An important part of this proposal is the development and application of the indirect coulometric titration and spectroelectrochemical methods using optically transparent electrodes. BIBLIOGRAPHIC REFERENCES: D.A. Yates and T. Kuwana, "Evaluation of a Self-Contained Linear Diode Array Detector for Rapid Scanning Spectrophotometry," , Anal. Chem., 48, (1976) March issue), in press. N.R. Armstrong, A.W.C. Lin, M. Fujihira and T. Kuwana, "Electrochemical and Surface Characteristics of Tin Oxide and Indium Oxide Electrodes,". Anal. Chem., 48, (1976) (April issue), in press.